Ionic Species Derived from Luminol

In protic systems - mostly water - oxygen alone is not sufficient but catalysts such as and many other transition metal ions, often as complex 

Irradiation with different types of high energy rays, pulse radiolysis or acoustical cavitation also cause luminol chemiluminescence in aqueous solution. All these physical sources are known to produce HO. radicals by homolysis of the water molecules. The most reasonable assumption is that in aqueous solution the necessary luminol species is a radical anion (39) which rapidly reacts with an appropriate oxidizing species either as the neutral species or after ionization. 

The oxidant must be hydrogen peroxide with metal ion or metal complex catalysts. With HO radical forming agents, molecular oxygen is sufficient. 

A striking feature in luminol chemiluminescence (and indeed in hydrazide luminescence generally) is the behaviour in two markedly different sets of conditions [30]. 

In aprotic solvents such as DMF, DMSO, or tetrahydrofuran, high chemiluminescence quantum yields are observed. The excitation yield 0es is about 0.09. This efficiency is not influenced to any considerable extent by temperature, polarity of solvent, or by quenchers. No catalyst other than very strong base is required. The oxidant is molecular oxygen. 

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